The net positive suction head of a boiler centrifugal feed pump should be calculated to include the feed water vapor pressure and the __________.
• Net Positive Suction Head (NPSH) definition and purpose • What causes cavitation in a centrifugal pump • How static head and system layout affect suction conditions
• Ask yourself: when calculating NPSH available at the pump, which physical factors at the suction side change the pressure at the pump eye? • Think about the location of the feed pump relative to the DC heater and the water surface – what vertical distance matters? • Which answer choices are properties of the pump itself versus properties of the system supplying the pump?
• Identify which options describe system suction conditions rather than pump design characteristics • Confirm that NPSH includes vapor pressure of the liquid at pumping temperature plus (or minus) the effect of liquid level above/below the pump centerline • Check which choice directly relates to the static suction head from the feed system (like a DC heater or hotwell) to the pump inlet
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